AURORA BOREALIS

(Northern Lights)

The  Aurora Borealis (Northern Lights) , also called Northern Lights, are a fascinating phenomenon. The brilliant dancing lights occur when highly charged electrons from the solar wind interact with elements in the earth's atmosphere. These geomagnetic disturbances are called substorms. A hail of high-speed electrons travel along magnetic field lines until they collide with the Earth's upper atmosphere. As the charged particles enter the earth's atmosphere, they will mix with atoms of oxygen and nitrogen at altitudes from 20 to 200 miles above the Earth. The color of the aurora depends on which atom is struck, and the altitude when the gases and the atoms meet.

Green - oxygen, up to 150 miles in altitude

Red - oxygen, above 150 miles in altitude

Blue - nitrogen, up to 60 miles in altitude

Purple/violet - nitrogen, above 60 miles in altitude

( http://stuff.dewsoftoverseas.com/bquestion471.htm )

According to historical records, geomagnetic disturbances are almost twice as likely to occur in the spring and autumn versus the seasons of summer and winter. These facts are related to the fact that magnetic connections between the sun and Earth occur primarily during equinoxes. These connections open the door for solar wind energy to flow inward and ignite the Northern Lights

THEMIS (Time History of Events and Macroscale Interactions during Substorms) is one of the leading research projects currently underway studying substorms and their relationship with the Aurora Borealis (Northern Lights) . THEMIS is a NASA-funded mission launched in Cape Canaveral, Florida on February 17, 2007. 

Dr. Vassilis Angelopoulos Photo Courtesy: UCLA

Vassilis Angelopoulos heads up this project at the University of California, Los Angeles. Angelopoulos is a Professor of Earth and Space Sciences as well as a member of the Institute of Geophysics and Space Physics at UCLA. THEMIS is hoping to observe approximately 30 substorms during the course of its research.

The same massively-charged electrons that spark the Northern Lights during a substorm can interfere with the functioning of satellites, power grids, and communications systems. Magnetospheric substorms can induce electric currents in power lines that result in blackouts due to overloaded equipment. Electrons with these energies can damage electronics on spacecrafts and even be a cause of cancer in unprotected astronauts. The quest by scientists to understand the wonder and workings of the aurora borealis have led them to discover some truly practical and useful information.